2019 UK Election - Grieve as PM, Brexit Party remains ahead

[Huey Long is a Republican]

We all know the result of the 2019 UK Gen Election which saw Boris Johnson sweep to maintain parliament for the tories for another 5 years, which have led to PM Sunak and the current situation the UK is in. However, what if Prominent Remainer Dominic Grieve defeated Boris for the Prime Minister-ship and declared a snap election with the promise of a second referendum in 2020 if he won. What Tory and Labour (if any) MPs would defect to Brexit (the MP and their seat), where would Nigel run for Parliament, and what would the result be if this happened as this means no BRX-CON coalition in seats to prevent vote splitting and a large chunk of the Leave base of the Tories likely goes whole hog for Brexit after having been betrayed by the party. What does Parliament look like in 2019 following the election?